We developed an uterine intraluminal infusion technique for delivery of exogenous factors to the reproductive tract. In these studies, adult monkeys were treated sequentially with implants of estradiol (E2) and E2 + progesterone (P) to induce artificial menstrual cycles. The monkeys were then laparotomized and an intraoviductal catheter was installed. In a preliminary study with this system, we infused 3H-thymidine into the tract in two monkeys treated with E2 alone. The locally infused thymidine penetrated deeply into the endometrium, labeling both stromal and glandular epithelial cells. The epithelial cells in the glands of the upper functionalis (which are the only glands that proliferate during estrogen treatment) were well labeled. The most intense labeling was in the stromal cells closest to the lumen, but stromal cells in deeper layers were also labeled. We then used this technique to deliver exogenous keratinocyte growth factor (KGF) locally to the endometrium. In this experiment, rhesus monkeys were laparotomized on day 14 of E2 + P treatment and an intraluminal catheter installed. The reproductive tracts were flushed (via the oviduct) with either 0.5 mg KGF or vehicle (PBS 1 ml) and then P implants were removed. KGF (or vehicle) was flushed through the tract daily for 4 days, and the tracts were then collected. Intraluminal treatment with KGF suppressed apoptosis in the endometrial basalis, stimulated glandular sacculation and secretion in the endometrial functionalis, and stimulated spiral artery growth. These effects were similar to effects observed after systemic treatment of juvenile monkeys with KGF under similar hormonal conditions during the luteal-follicular transition. In summary, this intraluminal infusion technique provides a dependable method for local treatment of the monkey reproductive tract with exogenous factors.